Ultra-Thick Metal (UTM) conductors have reduced resistance as compared to conventional metal layer leads. It is thus conventional to form UTM inductors to provide a high quality factor for RF filters and related circuits. To further increase the quality factor, the UTM conductors are deposited on low-k dielectric materials. To even further increase performance, the UTM conductors are deposited over extreme low-k (ELK) dielectric materials, which have a dielectric constant (k) of approximately 2.5 or less. It is difficult to engineer the dielectric constant so low such that ELK dielectric materials tend to be porous such as porous SiOCH. Although low k and ELK dielectrics advantageously enhance the electrical performance of the corresponding UTM structures, their porosity leads to poor mechanical strength. The tensile strength, hardness, and cohesive strength of ELK dielectrics are much lower than the corresponding strengths for traditional dielectric materials such as silicon dioxide. Delamination of the robust UTM conductors from low k and ELK dielectrics is thus problematic. To strengthen the dielectric layer to inhibit delamination, it is conventional to use a dummy metal fill outside of the UTM footprint. No dummy metal fill is used underneath (within the footprint) of the UTM conductor to prevent reduction of the resulting quality factor due to electrical coupling of the metal fill to the UTM conductor. But delamination remains a problem due to the poor mechanical strength of ELK dielectrics.
Accordingly, there is a need in the art for improving the strength of low-k dielectric and ELK dielectric to prevent the delaimination of UTM conductors.